The present invention relates to controls for multiple electrical power sources, in particular to controls for matching the available power to the demand.
In many situations it is desirable (or necessary) to obtain electrical power from grid isolated installations of electrical generators rather than from conventional electric utilities. This may be the sole source of electrical power or for backup power.
This situation presents problems that are not found in the electric utility context. Electric utilities normally have substantial spinning reserves of their own and interconnections with other utilities. Demand fluctuations tend to be relatively small with respect to the total load being served.
In a small electrical power installation, a single generator to handle the entire maximum expected demand can be used, but the generator is then typically under loaded and may be inefficient. In addition, this provides no backup if the single unit generator fails.
An installation which overcomes this problem uses two or more smaller generators that have a combined capacity capable of meeting or exceeding the maximum expected demand. This allows generators to be activated or deactivated to more closely match the demand with resulting maintenance of efficiency. With several smaller generators, sufficient excess capacity can be provided to allow for individual generator down time.